On a clear day it's not difficult to make your way to the summit of Snowdon. Even if you miss the signposts for the main tracks, there's always the trail of banana skins and plastic bottles to follow. Alternatively, you can tag along with any of the many groups wearily pushing on to the top in aid of charity. Or you can just pay £15 and catch the train from Llanberis, letting it take the strain of the 1,085 metre climb instead.
The Victorians are responsible for enabling 350,000 people to reach the summit each year. By building the UK's only rack-and-pinion railway here 112 years ago, they allowed the mountain to be "conquered" by everyone from ladies in crinolines and bonnets to the current flip-flop-wearing day tripper.
While walkers like to claim the moral high ground by getting there on foot, the coal and diesel-fuelled trains puff along at 5mph, taking an hour to reach their lofty destination. Until recently, this was an ugly concrete bunker-style building. Built in the 1930s by Clough Williams-Ellis (who also created and built the Italian-inspired village of Portmeirion nearby), it had seen its status decline over the years to become a "cafe and shop complex".
It wasn't the first building to grace the summit - in 1887, a hotel displayed a board outside saying "Bazaar and refreshments, well-aired beds, ham and eggs, choice beverages" - but Williams-Ellis's building suffered its ultimate indignity when, in the mid-1990s, Prince Charles declared it the "highest slum in Wales".
Around the same time, its owner, the Snowdonia National Park Authority (SNPA), launched an appeal for public backing to rebuild the cafe. In 2001, while still struggling to raise the estimated £4m required, it unveiled plans for a new "sustainable" building by architects Furneaux Stewart, who had worked on the Eden Project in Cornwall.
Five years later, thanks to a public appeal and £4m of funding from Europe, the scheme finally went ahead. But the money came with strings attached. The new "visitor centre", as the SNPO now likes to call it, which would now cost over £8m to build, would have to be completed no later than "early summer 2008" to qualify for the extra funding.
It was an ambitious deadline, even for a project at ground level, but one that has now been missed with the building still far from ready to serve a cup of tea or sell its first "I Climbed Snowdon" T-shirt.
The Welsh weather is largely to blame. A combination of snow in April and May this year and the wet summer last year conspired to delay construction even further. In the meantime, SNPA officers were able to agree on the new name for the building - Hafod Eryri ("Eryri" is the Welsh name for the mountain and "hafod" means "a dwelling on high land").
But while it may have a Welsh name, Hafod Eryri's roof - the highest in a nation that once proudly boasted that it had roofed the world with its famous slate - is actually made from granite blocks imported from Portugal. The decision provoked outrage in Wales, even though granite from nearby Blaenau Ffestiniog was later found for the walls and the floor.
Aneurin Phillips, the SNPA's chief executive, says he too was "very disappointed" about the roof, even though two-thirds of the building materials have still been sourced locally: "Unfortunately, [the site's builders] Carillion, who shouldered the risk of completing this building, decided on the source of the stone and said it wanted to source it quickly for contractual reasons. Local stone was more expensive, but my understanding is that local suppliers also could not commit to the delivery timetable required by Carillion and shoulder any cost from failing to deliver on time."
Meanwhile, the debate over whether there should even be a building at the summit rumbles on, as it has done since the 19th century. The Council for the Protection of Rural Wales (CPRW) says it would oppose plans for building on any other mountain, but Snowdon is an exceptional case.
"It is a building that was needed," says CPRW director Peter Ogden, "but I have got reservations about whether it needed to have been on the summit or whether it couldn't have been built further down."
Rob Collister, a mountain guide who is the North Wales representative of mountain preservation charity the John Muir Trust, agrees: "The fumes the railway gives off are diabolical and the smell at the summit is terrible. Sadly, there was no chance of getting rid of it, but this would have been an opportunity to put some sort of centre further down the mountain. It is also a ridiculous sum of money to spend on a tourist attraction."
But Phillips defends the new building: "It hasn't been a wild summit for 200 years. There wasn't an option to build something lower down because it would affect another part of the mountain that was unspoiled. It made more sense to build in the same footprint as the existing one."
As the arguments continue at ground level, the 71-strong workforce battles with the weather at the top. Their deadline to complete the work- including the European funding deadline - has been extended to September, because of the unpredictable conditions.
In the 18 months they been building, instead of losing an anticipated 60 days to bad weather, 130 days were written off. At times, when the winds have been too strong for the trains to safely reach them, the builders have had to crawl part way down the mountain on their hands and knees.
Much is made of Hafod Eryri's eco-friendly credentials: it harvests rainwater for all the toilets, windows are tilted to minimise light reflection and shutters eliminate light pollution. Thermal panels reduce the heating costs, while acoustic panels absorb noise from the generator, which powers the building.
But the building is not as sustainable as it could be: the summit was considered too windy for a wind turbine and solar panels were seen as too vulnerable to vandalism. Drinking water, meanwhile, is brought up on the railway which, twice a year, carries all of the building's sewage off the mountain.
When Hafod Eryri is finally completed, the trains will bring up all the ingredients for the promised "locally sourced menu" but until then, the builders can ignore the controversy over the construction materials and the placement of the building, and instead admire the ever-shifting view from Britain's highest building site as they eat their lunch.
"There was one day last week when we could see the Isle of Man and Ireland," says assistant site manager George Owen. "Two-and-a-half years I've been working up here and that was the first time".
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